Hiroko Maruyama

Objective 2-[¹⁸F]fluoro-2-deoxy-d-glucose positron emission tomography ([¹⁸F]-FDG-PET) is a imaging modality that has been used to measure of glucose metabolism in the brain in Alzheimer’s disease (AD). Clinically, decreased glucose uptake has been reported in the brain of AD, although the precise underlying mechanisms have not yet been elucidated. To elucidate the mechanisms of decreased [¹⁸F]-FDG uptake in the AD by PET, [¹⁸F]-FDG uptake in the brain of aged model mouse of AD was investigated using a dynamic autoradiography technique “bioradiography”. A X-ray phase-contrast imaging (X-PCI) and a histopathological evaluation were also investigated to elucidate the mechanisms underlying the relationships between decreased [¹⁸F]-FDG uptake and the pathological changes in the brain of AD mouse. Methods In this study, AD model mouse (5XFAD, APP⁺/PS1⁺) were used. [¹⁸F]-FDG-bioradiography was conducted in fresh slices of brain tissue under the condition of resting (slices immersed in 5 mM K⁺ solution) and metabolically active (in 50 mM K⁺ solution). Amyloid β42 (Aβ42) deposition in the brain of AD mouse was confirmed by X-PCI. In addition, the positive cells of phosphated tau protein (P-tau) and deposition of Aβ42 were also examined by immunohistochemical staining. Results No significant differences were observed between the two groups in the resting condition. In the activate condition of the brain, [¹⁸F]-FDG uptake was significantly decreased in AD mice compared to WT mice. In X-PCI showed Aβ deposition in the AD mouse, but not in the WT. The AD mouse also showed increased P-tau, accumulation of Aβ42, increase in neuronal apoptosis, and decrease in the number of neurons than that of the WT mouse. Conclusion Neuronal damage, and induction of neuronal apoptosis, decreased [¹⁸F]-FDG uptake, increased Aβ accumulation and P-tau induced neurofibrillary degeneration are observed in AD mouse. In clinical diagnosis, reduction of [¹⁸F]-FDG uptake by PET is one of the means of diagnosing the onset of AD. Our results suggest that decreased uptake of [¹⁸F]-FDG in the brains of AD may be associated with neuronal dysfunction and cell death in the brain.

Objective 2-[¹⁸F]fluoro-2-deoxy-D-glucose Positron Emission Tomography ([¹⁸F]-FDG-PET) is a imaging modality that has been used to measure of glucose metabolism in the brain in Alzheimer’s disease (AD). Clinically, decreased glucose uptake has been reported in the brain of AD, although the precise underlying mechanisms have not yet been elucidated. To elucidate the mechanisms of decreased [¹⁸F]-FDG uptake in the AD by PET, [¹⁸F]-FDG uptake in the brain of aged model mouse of AD was investigated using a dynamic autoradiography technique “bioradiogaraphy”. A X-ray phase-contrast imaging (X-PCI) and a histopathological evaluation were also investigated to elucidate the mechanisms underlying the relationships between decreased [¹⁸F]-FDG uptake and the pathological changes in the brain of AD mouse.Methods In this study, AD model mouse (APP⁺/PS1⁺) were used. [¹⁸F]-FDG-bioradiography was conducted in fresh slices of brain tissue under the condition of resting (slices immersed in 5 mM K⁺ solution) and metabolically active (in 50 mM K⁺ solution). Amyloid β42 (Aβ42) deposition in the brain of AD mouse was confirmed by X-PCI. In addition, the positive cells of phosphated tau protein (P-tau) and deposition of Aβ42 were also examined by immunohistochemical staining.Results In the metabolically active condition, [¹⁸F]-FDG uptake was significantly enhanced in the WT mouse but not significant in the AD mouse, whereas in resting condition, no significant difference was observed between two groups. In X-PCI showed Aβ deposition in the AD mouse, but not in the WT. The AD mouse also showed increased P-tau, accumulation of Aβ42, increase in neuronal apoptosis, and decrease in the number of neurons than that of the WT mouse.Conclusion Neuronal damage, and induction of neuronal apoptosis, decreased [¹⁸F]-FDG uptake, increased Aβ accumulation and P-tau induced neurofibrillary degeneration are observed in AD mouse. In clinical diagnosis, reduction of [¹⁸F]-FDG uptake by PET is one of the means of diagnosing the onset of AD. Our results suggest that decreased uptake of [¹⁸F]-FDG in the brains of AD may be associated with neuronal dysfunction and cell death in the brain.

Type 2 diabetes mellitus (T2DM), a lifestyle-related disease, is developed due to eating habits and decreased physical activity. Diabetes also increases the risk of cancer and major neurodegenerative diseases; controlling the onset of diabetes helps prevent various illnesses. Eating seaweed, such as Undaria pinnatifida (wakame), is a part of the Asian food culture. Therefore, we analyzed the antidiabetic effect of wakame intake using the high-fat diet-induced diabetes mouse model. Furthermore, we analyzed the effect of wakame extract on the cell membrane translocation of glucose transporter-4 (GLUT4) and activation of insulin signal molecules, such as AKT and AMPK, in insulin-sensitive tissues. Differentiated C2C12 cells were incubated with wakame components. The membrane translocation of GLUT4 and phosphorylation of AKT and AMPK were investigated with immunofluorescence staining and Western blotting, respectively. Also, male C57BL/6J mice were fed the normal diet (ND), high-fat diet (HFD), ND with 1 wakame powder (ND+W), or HFD with 1 wakame powder (HFD+W). We evaluated the effect of wakame intake on high-fat diet-induced glucose intolerance using an oral glucose tolerance test. Moreover, we analyzed insulin signaling molecules, such as GLUT4, AKT, and AMPK, in muscle using Western blotting. GLUT4 membrane translocation was promoted by wakame components. Also, GLUT4 levels and AKT and AMPK phosphorylation were significantly elevated by wakame components in C2C12 cells. In addition, the area under the curve (AUC) of the HFD+W group was significantly smaller than that of the HFD group. Furthermore, the level of GLUT4 in the muscle was increased in the wakame intake group. This study revealed that various wakame components exerted antidiabetic effects on the mice on a high-fat diet by promoting glucose uptake in the skeletal muscle, enhancing GLUT4 levels, and activating AKT and AMPK.

Aim: Gynura procumbens (Lour.) Merr. (GP) has drawn attention as an alternative drug for the treatment of diabetes mellitus. However, while most previous studies were done in diabetic mice to investigate the antidiabetic effect, this study investigated the blood glucose‐lowering action of GP in diet‐induced obese mice and clarified the possible mechanism of the glucose‐lowering action of GP in muscle and adipose cells.Methods: The mice were divided into four groups (n = 6 in each group) depending on the diet that they received (i.e., the normal diet (ND), normal diet + 1% GP powder (ND + GP), high‐fat diet (HFD), high‐fat diet + 1% GP powder (HFD + GP) groups), and the oral glucose tolerance test (OGTT) was performed after one, three and five months. Immunocytochemistry revealed GLUT4 translocation in cells stably expressing myc‐GLUT4‐ECFP. The effect of GP extracts on the expression of GLUT4 and phosphorylation of 5'‐adenosine monophosphate‐activated protein kinase (AMPK) and Akt/protein kinase B (PKB) in C2C12 (muscle cell) and 3T3‐L1 (adipocyte) cells, was determined by western blot analysis.Results: The results showed that the significantly raised serum glucose levels in the HFD group were reduced following treatment with GP powder. Moreover, treatment with the GP extracts promoted GLUT4 membrane translocation more prominently in the C2C12 cells as compared to the 3T3‐L1 cells, whereas GLUT4 expression was significantly increased only in the 3T3‐L1 cells. AMPK phosphorylation was significantly increased by both extracts in both C2C12 cells and 3T3‐L1 cells.Conclusion: The findings of the present study reveal that GP may correct glucose intolerance and both the ethanolic and water extracts of GP have a blood glucose‐lowering effect, possibly via AMPK‐mediated signaling pathways in the muscle and adipose tissues.

It is well known that ultraviolet B irradiation leads to dermal inflammation. In this study, we found that Mekabu fucoidan suppressed edema, decreased the thickness of the prickle cell layer, and decreased matrix metalloproteinase 1 in the skin of mice irradiated with ultraviolet B. Moreover, we found that the mean level of interferon gamma of Mekabu fucoidan-treated, ultraviolet B-irradiated mice (approximately 2.2 ng/mL) was not significantly different from that in normal mice (approximately 2.5 ng/mL). In contrast, a significant decrease in the mean level of interferon gamma (approximately 1.3 ng/mL) in ultraviolet B-irradiated control mice was observed compared with that in Mekabu fucoidan-treated, ultraviolet B-irradiated mice. The mean thickness of the prickle cell layer in the skin of Mekabu fucoidan-treated, ultraviolet B-irradiated mice was less than that in the ultraviolet B-irradiated control mice. Metalloproteinase 1 activity was significantly higher in the skin of ultraviolet B-irradiated mice than in the skin of untreated, nonirradiated normal mice. Metalloproteinase 1 in the skin of ultraviolet B-irradiated, Mekabu fucoidan- or L(+)-ascorbic acid (vitamin C)-treated mice was significantly lower than that in the ultraviolet B-irradiated control mice. Mitigation of the morphological changes in Mekabu fucoidan-treated mice was correlated with a decrease in metalloproteinase 1 levels. These data indicate that Mekabu fucoidan is an effective suppressor of inflammation in an ultraviolet B-irradiated mouse model.

Fucose-containing sulfated polysaccharides (FCSPs) extracted from seaweeds, especially brown macro-algae, are known to possess essential bioactive properties, notably growth inhibitory effects on tumor cells. In this work, we conducted a series of in vitro studies to examine the influence of FCSPs products from Sargassum henslowianum C. Agardh (FSAR) and Fucus vesiculosus (FVES), respectively, on proliferation of melanoma B16 cells and to investigate the underlying apoptosis promoting mechanisms. Cell viability analysis showed that both FCSPs products, i.e., FSAR and FVES, decreased the proliferation of the melanoma cells in a dose-response fashion, with FSAR being more potent at lower dosages, and FVES being relatively more anti-proliferative than FSAR at higher dosages. Flow cytometric analysis by Annexin V staining of the melanoma cells exposed to the FCSPs products confirmed that both FSAR and FVES induced apoptosis. The FCSPs-induced apoptosis was evidenced by loss of plasma membrane asymmetry and translocation of the cell membrane phospholipids and was accompanied by the activation of caspase-3. The FCSPs bioactivity is proposed to be attributable to distinct structural features of the FCSPs, particularly the presence of sulfated galactofucans (notably in S. henslowianum) and sulfated fucans (notably in F. vesiculosus). This study thus indicates that unfractionated FCSPs may exert bioactive effects on skin cancer cells via induction of apoptosis through cascades of reactions that involve activation of caspase-3.

The direct interaction of Mekabu fucoidan (meFucoidan) with four functional basic proteins (sPLA2-IIA, bFGF, histone H2B and HBV core protein) and three synthetic FGF-BP peptides (sp5, GE13 and RS6) was characterized in vitro. It was found that (i) meFucoidan inhibited dose-dependently the activity of sPLA2-IIA, but not pPLA2, through its direct binding to the enzyme; (ii) sPLA2-IIA activity was sensitive to meFucoidan rather than heparin, but significantly stimulated by sulfatide; (iii) the A-kinase-mediated phosphorylation of these basic proteins, except sPLA2-IIA, and synthetic peptides, containing potent phosphorylation sites for A-kinase, was inhibited dose-dependently by meFucoidan; and (iv) two consensus meFucoidan-binding motifs (B-B-B-B-X and B-X-B-B-X; B, basic amino acid) in these basic proteins and synthetic peptides could be overlapping to the potent phosphorylation site (B-B-X-S/T) for the kinase in vitro. These results presented here suggest that meFucoidan functions as a selective inhibitor for sPLA2-IIA and the A-kinase-mediated phosphorylation of cellular meFucoidan-binding functional basic proteins in vitro.

Fucoidan from Mekabu (sporophyll of Undaria pinnatifida), a dietary alga, exerts antitumor activity possibly through enhancing the immune response. The present report describes the effects of dietary Mekabu fucoidan on the tumor growth of mouse A20 leukemia cells and on T cell-mediated immune responses in T cell receptor transgenic (DO-11 - 10 - Tg) mice. The animals were fed with a diet containing 1 % Mekabu fucoidan (0.034 ± 0.003 g/mouse/day) for 10 days and subcutaneously (s. c.) inoculated with A20 leukemia cells. Thereafter, the mice were fed with the diet containing fucoidan for 40 days. Mekabu fucoidan inhibited tumors by 65.4 %. We studied how the killer activities of T cell-mediated and natural killer (NK) cells are augmented in DO-11 - 10 mice fed with Mekabu fucoidan. The cytolytic activities of ovalbumin (OVA), which is specific against OVA-transfected A20 (OVA-A20) B lymphoma cells, and NK cells against YAC-1 were significantly enhanced in the mice fed with fucoidan compared with a basic diet. Thus, these findings suggested that Mekabu fucoidan mediates tumor destruction through Th1 cell and NK cell responses.